One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The USDA zone info for Romeoville can be looked at to estimate when it's the best time to plant sweet williams.

Planting Calendar for Sweet Williams

Frost tolerance for sweet williams:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Sweet Williams tend to make it in mild cold which means that you can plant them just a bit earlier in the year than more sensitive plants.

The earliest that you can plant sweet williams in Romeoville is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant sweet williams and expect a good harvest is probably September. You probably don't want to wait any later than that or else your sweet williams may not have a chance to really do well. Starting your sweet williams indoors is a great way to get them started a few weeks earlier.

Last Frost Date

On average the last frost is on April 15 in Romeoville. In the coldest months of winter you should expect an average low temperature of -15°F.

Since the USDA zone info for Romeoville is just an average the actual date of last frost can change quite a bit from year to year. Half of the time in Romeoville you get a frost after April 15 so make sure that you are prepared to cover your sweet williams if you have a late frost.

USDA Zone Info for Romeoville

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-15°F
Highest Expected Low	-10°F

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Romeoville

You may be interested in your other planting guides for Romeoville.